Electrocoagulation reactor

ABSTRACT

An electrocoagulation reactor is provided for treating waste water and removing contaminants therefrom. The reactor is typically a six-sided rectangular water-tight housing which has an inlet pipe and an outlet pipe. There are a multiplicity of charged plates located parallel to one another within the housing. Adjacent plates are typically oppositely charged and water will pass between the plates as it flows through the reactor. The electric field between the plates will help encourage coagulation of waste matter which then may be removed from the waste water downstream of the electrocoagulation reactor.

RELATED PATENTS

This application claims priority, is a continuation from, andincorporates herein by reference U.S. patent application Ser. No.11/581,695filed Oct. 16, 2006, which claims priority and is acontinuation from U.S. patent application Ser. No. 10/171,926, filedJun. 14, 2002; which claims priority from U.S. Patent Application Ser.No. 60/318,730, filed Sep. 12, 2001; which is also herein incorporatedby reference.

This application is related to U.S. patent application Ser. No.08/976,695, filed Nov. 24, 1997, PCT/US98/24885, filed Nov. 23, 1998,U.S. patent application Ser. No. 09/554,975, filed Jul. 7, 2000, andU.S. patent application Ser. No. 09/961,524 filed Sep. 24, 2001, whichare all herein incorporated by reference.

FIELD OF THE INVENTION

Electrocoagulation reactors, more specifically, a electrocoagulationreactor with the plates in parallel to the flow of the water.

BACKGROUND OF THE INVENTION

Wastewater, such as wastewater from factories or manufacturing plants,must be treated for contaminants before it is discharged into theenvironment. Water for use in industrial or other manufacturing processoften requires treatment before use to alter its chemical or physicalcharacteristics. Electrocoagulation is an electro chemical process thatsimultaneously removes heavy metals, suspended solids, organic and othercontaminates from water using electricity instead of expensive chemicalreagents. Electrocoagulation was first used to treat bilge water fromships. The Electrocoagulation process passes contaminated water betweenmetal plates charged with direct current. While the term “wastewater” isoften used herein, the term is to be understood to mean any water fromwhich one may wish to remove a “contaminant” even though the contaminantmay not necessarily be a material that would be harmful to ones health.

Additional background in the specifications regardingelectrocoagulations may be found in U.S. Pat. No. 5,928,493, thespecifications or drawings of which are incorporated herein byreference.

Applicant's provide, in the invention disclosed herein, an unpressurizedelectrocoagulation reactor, with plates in parallel to the flow of thewater, which reactor has the capability of treating a higher flow ofwastewater than has heretofore been available.

SUMMARY OF THE INVENTION

Applicants provide for these and other objectives in a parallel flowreactor comprised of one or more reactor cells. Each cell typicallyincludes a tank containing a cartridge, the cartridge having a framewith a multiplicity of aligned plates therein. Water flows through thetank, typically up from the bottom of the cartridge-held plates over atop wall of the cartridge in “water fall” (cascading) fashion and outthe tank for further processing or use. Applicant provides anelectrocoagulation cell with an open top, one that is unpressurized andobtains, at least in part, the flow of water under the impetus ofgravity.

Applicants provide for these and other objectives in anelectrocoagulation reactor comprising, in a preferred embodiment, twoelectrocoagulation cells placed “in series.” By “in series” applicantmeans that a molecule of wastewater will flow between two adjacent platein the first cell of a reactor, out of the first cell of the reactor andbetween a second pair of plates in the second cell of theelectrocoagulation reactor. Applicants provide, in a preferredembodiment of a two-cell electrocoagulation reactor, cells which are setin series. This is to be compared with the arrangement in a “seriesflow” reactor in which a single molecule of water would follow aserpentine path and pass between a multiplicity of plate pairs within asingle cell.

Applicants provide for these and other objectives in a parallel flow,open top electrocoagulation reactor having one of more cells in series,wherein each cell typically contains a cartridge capable of being liftedout of the tank of the cell. In other words, applicants provide for a“cartridge” which is capable of receiving plates therein, and thendropped into, from the open top, the tank of a electrocoagulation cell,and, when the plates need replacement, the cartridge may be lifted outof the electrocoagulation tank so that the used up plates may be changedout with new plates at a point removed from the electrocoagulation tank.This and other advantages of applicant's cartridge will be apparent withreference to specifications and drawings contained herein.

Applicants' unique cartridge also provides for the ability to acceptplates of differing dimensions so, for example, a single cartridge mayeither receive plates with a given height, or, if the user requires lesstreatment capacity, to receive plates of a shorter or greater height.Thus, a user may, instead of using a reactor with a different size tank,simply use the same tank and same cartridge, but use, if the conditionsrequire, plates with less or greater surface area.

Applicants provide for efficient treatment of wastewater in a parallelflow, open top, cartridge-receiving electrocoagulation cell in whichthere are a multiplicity of plates, at least some of the plates beingalternately charged positive and negative, sometimes with an“intermediate” or uncharged plate (or plates) between adjacent positiveand negative plates.

Applicants provide for these and other advantages and objects in anelectrocoagulation reactor consisting of electrocoagulation cells inwhich, beneath the plate bearing cartridges and in fluid communicationtherewith is a solids sump with a drain attached thereto for removingfrom a tank of the electrocoagulation cell, waste sediment that hasresulted from the electrocoagulation of waste particles and for removalof the collected sediment from a drain therein.

Applicants provide for these and other advantages and objectives, in anelectrocoagulation reactor system comprising a unique stand forcooperatively engaging the tank and cartridge of the electrocoagulationcell to provide direct weight-bearing support of the plates in thecartridge of the electrocoagulation cell.

Applicants additionally provide a plate for use with any type ofelectrocoagulation reactor system, which plate contains cutouts in thewalls there through, the cutouts for more effective treatment ofwastewater passing adjacent the plate.

Applicants additionally provide, for use with any reactor, arecirculation pump and recirculation loop. The recirculation pump andloop takes some, but not all, of the water flowing out of a reactor andrecirculates it through the reactor by, typically, routing it upstreamof the intake of the reactor. This allows the user to maintain a greaterflow of fluid through the reactor than the net flow of water treated.

Applicants also provide for a novel dissolved air floatation cell forthe treatment of wastewater using an electrocoagulation reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an isometric view of a single parallel flow cell.

FIG. 1A is a side elevational view of a pair of parallel flow reactorcells in series.

FIG. 1B is a partial elevational view of a multiplicity of parallelplates for use in Applicants' novel electrocoagulation reactor.

FIGS. 1C and 1D are partial side elevational views illustrating themanner in which Applicants' cartridge may be modified to contain platesof different heights.

FIG. 1E is a partial isometric view of a device and method for raisingthe height of the weir of Applicants' electrocoagulation cell byattaching a riser thereto.

FIG. 1F illustrates a device for maintaining separation between the wallof the tank and the wall of the cartridge, in partial view, cutawayisometric.

FIG. 2 illustrates a side elevational view of a parallel flowelectrocoagulation reactor.

FIG. 3 illustrates a front view of the electrocoagulation cellillustrating a pair of drains 12H to remove liquids therefrom.

FIG. 4 illustrates an isometric view of two parallel reactor cells in asingle tank.

FIG. 5 is a front elevational view of a single reactor tank having apair of cartridges therein and a multiplicity of circulation drains andinlets.

FIG. 6 is a rear view of the illustration set forth in FIG. 5 above.

FIGS. 7A-E are various view of a stand for use with Applicants'electrocoagulation reactor.

FIGS. 8A and 8B are isometric views of different embodiments of platesfor use in Applicants' electrocoagulation reactor.

FIGS. 9 and 10 are block diagrams of Applicants' novel recirculationpump and recirculation loop for use with a wastewater reactor.

FIGS. 11A and 11B are side and bottom elevational views of a dissolvedair floatation cell for use with Applicants' electrocoagulation reactor.

FIGS. 12A and 12B are alternate preferred embodiments of a dissolved airfloatation cell for use with Applicants' waste treatment process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning to FIG. 1 it is seen that applicant provides anelectrocoagulation reactor 11 which may be comprised of a singleelectrocoagulation cell 10 or two or more electrocoagulation cells 10and 10A placed in series, see FIG. 1A.

Attention will be first directed to FIG. 1 to explain the structure andfunction of an electrocoagulation cell 10. Once this is understood, itwill be seen that the structure and function of electrocoagulation cell10 is nearly identical to second cell 10A (See FIG. 1A). Turning back toFIG. 1, it is seen that first electrocoagulation cell 10 is comprised ofa typically open topped cell tank 12 and a first cartridge 14 restinginside the tank 12 in wastewater WW. Tank 12 is typically watertight andmay be rectangular, or any other shape and typically includes an opentop 12Q. In any case, cell tank 12 is typically unpressurized and may bemade of fiberglass, steel or plastic, or in fact any other suitablematerial which would provide watertight sealing and would not react withthe wastewater. Cell tank 12 is seen to have, in the preferredembodiment illustrated in FIG. 1, four sidewalls, 12A, 12B, 12C and 12Dset perpendicular to one another so as to provide the rectangularstructure illustrated as cartridge receiving portion 12I of the tank 12.Depending below cartridge receiving portion 12I and integral therewithand in fluid communication with cartridge receiving portion receiving12I is sump portion 12J of tank 12. It is seen with reference to FIG. 1that cartridge receiving portion 12I has an open bottom 12R. It is alsoseen that cartridge receiving portion 12I of cell tank 12 includes arectangular cartridge support ledge 12F and a cartridge support anddrain ledge 12G. The four ledges directed inboard along the perimeter ofthe sidewalls act as a base to hold the cartridge 14 along the loweredges, so water may enter the cartridge from below. The function of theledges is to support the lower perimeter of the first cartridge 14 as itrests in cartridge receiving portion 12I. Additional features of celltank 12 include an upper perimeter 12E defined by the upper edges ofsidewalls 12A, 12B, 12C and 12D. Depending below cartridge support anddrain ledge 12G are one or more drains 12H which will accept wastewaterfrom a transfer chamber 13 (see FIG. 1A). The transfer chamber 13 is thespace between a front wall 14B of the cartridge 14 and sidewall 12A ofthe cell tank 12.

Turning now to sump portion 12J it is seen that this portion of celltank 12 is located below open bottom 12R of cartridge receiving portion12I so as to collect waste solids and suspended materials settling outfrom between plates 20 of first cartridge 14 (see FIG. 1A), at thebottom thereof for removal through a sump drain 12P. Sump portion 12Jtypically includes one or more canted or slopped sidewalls here showingfour sidewalls designated 12K, 12L, 12M and 12N so as to funnel, underthe impetus of gravity, settling solids to sump drain 12P for removaltherefrom.

It is seen that first cartridge 14 is typically not mechanicallyfastened to cartridge receiving portion 12I or any other portion of celltank 12, but merely rests along a portion of the bottom of cartridgereceiving portion 12I here resting along the edges below rear wall 14Aand front wall 14D on cartridge support ledge 12F and cartridge supportand drain ledge 12G, respectively and on ledges below the sidewalls ofthe cartridge. First cartridge 14 is typically rectangular shaped anddimensioned for the receipt within cartridge receiving portion 12I ofcell tank 12 so as to allow water coming in through inlet 13M tocirculate up through a pair of adjacent plates 20 and to cascade overthe weir 14J (or top lip) of front wall 14B into the transfer chamber 13(See FIG. 1A). In other words, a close examination of first cartridge14D as set forth in FIG. 1 will reveal that rear wall 14A and the twoend walls 14C and D are the same height but that front wall 14Bcomprises an upper perimeter or lip defining a weir 14J that is lower.

Moreover, both rear wall of 14A and front wall 14B have vertical slots14E on their inner faces for the acceptance of plates 20 in “slottingfashion.” Plates 20 are held along a pair of removed vertical edges andsuspended between the front wall 14B and the rear wall 14A with theentire cartridge having an open top 14H and an open bottom 14I for waterto pass up through the plates 20 as illustrated in FIG. 1A. It is seenthat first cartridge 14 also includes handling straps 14G which maycontain a hole at the removed ends thereof. The straps may extend downthe vertical sides of the cartridge 14 and beneath the walls to supportthem from below, and above the walls of the cartridge 14 to engage oneor more of hooks (not shown) to provide a mechanical assist to lift theentire cartridge 14, with the plates 20 therein, out of the open top 14Hof the tank 12 for replacement of the used up plates of the cartridge14, “offline.” Following plate 20 replacement, the cartridge 14 isreinserted into the tank.

The function of first cartridge 14 is to provide structure to define andmaintain a passageway for water entering through one or more inlet 3 13Msuch that the water will pass through a space between a pair of amultiplicity of pairs of plates 20 maintained between the front and rearwalls of the cartridge 14, in such a manner that the water spills overweir 14J into transfer chamber 13 for leaving cell tank 12 through drain12H. As the wastewater proceeds between the pair of oppositely chargedplates 20 and any intermediate plates therebetween it will be subject toan electric field which will promote electrocoagulation processes knownin the prior art.

FIG. 1A illustrates that a preferred alternate embodiment of applicants'present invention uses a second electrocoagulation cell 10A placed inseries with the first electrocoagulation cell 10, the combination beingreferred to as electrocoagulation reactor 11. That is, it is seen thatFIG. 1A illustrates raw water WW (untreated water) entering throughinlet 13M and passing between the plates of first cartridge 14 and thenpassing over weir 14J and out drain 12H. It is seen that the water thenpasses into inlet 16M of second tank 16. It is seen that second celltank 16 includes a second cartridge 18 which is substantially identicalto first cartridge 14 in all material components thereof and itsfunction. Water overflowing second weir 16J into transfer chamber 13Awill exit the electrocoagulation reactor 11 through drain 16H (assumingthis is only a two-cell reactor). It is found that providing two cellsin series, the second cell either being lower or having a weir lowerthan the first cell 10 allows water to flow through the cells under theimpetus of gravity (no pump necessary). Further, the use of a pair ormore of series engaged cells has proven to be effective in removingcontaminants from the water. While each of the two cells illustrated inFIG. 1A includes its own separate tank 12 and 16, respectively, it ispossible to set up a single large tank for two individual cells, eachcell being defined by its own cartridge and, further defined, by thepassageway of a single water molecule through a single pair of plates inthe first cartridge, and then passing through a single pair of adjacentplates in the second cartridge and then out the cell or tank. Applicantsmay provide a reactor containing two or more cartridges set up inseries, each cartridge with its own tank as illustrated in FIG. 1A.

FIG. 1B illustrates a top elevational view of a portion of the sidewalland end wall of a cartridge and the manner in which positively andnegatively charged plates may carry an intermediate or uncharged platetherebetween to assist in the effectiveness of the electrocoagulationprocess. That is, FIG. 1B illustrates a multiplicity of parallel platesincluding a positively charged plate 20A, intermediate (neutral oruncharged) ungrounded plate 20B and a negatively charged plate 20C.These plates are attached to a rectifier and the voltage therebetweenmay be adjustably set, typically to between zero and up to 50 volts DC.

In a preferred alternate embodiment there may be more than one immediateor neutral plate between adjacent positively or negatively chargedplates or, there may be no neutral plates at all between adjacentnegatively and positively charged plates. However, it is seen thatwhatever configurations the sets may take they are disposed parallel toone another as set forth in FIG. 1B.

In first preferred embodiment in cartridge 14/18, the plates 20, as seenin FIG. 1A will extend from at or near the top of the cartridge to at ornear the bottom of the cartridge. That is, the bottom edge of themultiplicity of plates may be adjacent to the top and bottom of thecartridge. However, applicants provide in a novel cartridge means toaccept shorter plates, that is, plates that do not extend fully down tothe bottom of the cartridge, in an effort to control the effectivenessand handling of the cartridge of the cell when handling a waste waterload that is less than the maximum capacity of the reactor.

As a bit of background, reactors are typically rated in their ability tohandle wastewater by the maximum amount of wastewater flow that can betreated by a given reactor. For example, a reactor may be designed totreat wastewater with a given conductivity/resistivity range at a flowof 500 gallons per minute. This rating for that given reactor is for areactor with full plates as illustrated in 1A. However, the situationmay arise where, for example, water with reduced flow rate is beingtreated and therefore the same applied voltage, say, for example, 48volts may be used but the user may “size” the cartridge with smallerplates for easier handling and increased efficiency. It is found to beadvantageous to use the same cartridge and provide a means for insertingshorter plates so as to efficiently handle wastewater with a lower flowrate than the maximum capability of the reactor cell. For example, auser may wish to purchase a cell of 500 gallons per minute maximumcapacity even though the current demand of that user is only, say, 200gallons per minute. It may be more economical to purchase a larger unitand use shorter plates and, when the requirements of the user increaseto use the same cartridge and purchase longer plates. Applicants haveprovided for a mechanism in their unique cartridge system which willallow for the acceptance of shorter plates therein.

To “size” a reactor, one could build eight to ten different size tanksand cartridges to cover the different flow rate demands from, forexample, 100 gallons per minute to 1500 gallons per minute. However, byusing Applicant's design one can cover the entire range with only twodifferent size tanks and cartridge by creating a flexible cartridgesystem allowing use of different size plates. In this way, a singlecartridge design can be used to accommodate flow rate demands from 100gallons per minute to 500 gallons per minute and another singlecartridge design can accommodate flow rate demands of 500 gallons perminute to 1500 gallons per minute. This system is illustrated in FIGS.1, 1C, 1D and 2. It is noted that both the front and the rear wall havea horizontally cut notch at a pre-described location above the bottomedge of the front and the rear wall. Notch 22 is dimensioned for snugreceipt of a stop member (24), typically a rectangular, elongated membersized to wedge snugly into notch 22. With notch 22 along the insidesurface of both the front wall and the rear wall the same distance abovethe bottom edge of each of those walls and with the stop members (24)firmly inserted in the notches, the cartridge can accept a shorter plateby receiving the lower edge of the plates (20) against the upper surfaceof the stop member 24 (See FIG. 1D).

Moreover, with water being treated at less than the maximum ratedcapacity, it is beneficial to raise the height of weir 14J/16J todecrease the amount of “freeboard” or the amount of exposed plate abovewater level WL (exposed plate is “wasted” when the rest of the plate isbeing consumed). A method for increasing the height of weir 14J/15J isillustrated in FIG. 1E. It is seen with respect to FIG. 1E a riser 26may be provided which is simply a rectangular, elongated member shapedto fit on top of weir 14J/16J by means, for example, of a dowel 26A/hole26B combination as illustrated in FIG. 1E. That is, a series ofvertically aligned holes 26B may be provided projecting downward fromthe top surface of weir 14J/16J and a pair of identically spaced anddimensioned holes provided in riser 26 projecting from the underside ofriser 26 up into the riser 26. With this arrangement, holes in the riserand weir dowels 26A may be used to snugly seat riser 26 to weir 14J/16Jto effectively raise the level the water which will reach before itpours over the weir 14J/16J and, likewise, would decrease the amount of“freeboard” on the steel plates. The reason for decreasing the amount offreeboard is that it represents waste of the plate. Ideally, thereshould be almost no freeboard and the entire plate should be consumed inthe electrocoagulation process.

Applicant's concept of sizing the plates for a flow rate of less thanthe maximum capacity of the electrocoagulation cell at a given voltagefor a given set of treatment parameters for water gives the user thepossibility of using a single “universal” cartridge—that is, a cartridgewhose plates or other variables can be sized so that it will effectivelyrun water with requirements substantially less than the maximumcapability of the unit, through the use of smaller plates. Smallerplates are, again, advantageous as they make handling of the cartridgewhich, loaded with plates, may weigh several thousand pounds, mucheasier. Applicants' provide for a universal cartridge with the abilityto easily alter the cartridge to accept the plates with differingdimensions, while also being able to alter the weir 14J/16J height ofthe cartridge 14 to adapt to the smaller plates. Some of theelectrocoagulation cells can use up to 7,000 pounds of steel plates in asingle cartridge. Therefore, the decreased lift-out and handlingrequirement may be readily appreciated.

One could lift out Applicants' cartridge, which consists of a framearound the plates, and then, with the cartridge removed from the tank,change out the plates. In other words, plates don't have to be changedout directly from the tank. Indeed, one can withdraw one cartridge andimmediately insert a second cartridge, full of plates and, at theirleisure, remove the wasted steel plates from the first cartridge. Inother words, the lift out cartridge provides that the plates can beremoved “in mass” and “replaced in mass,” a system where theelectrocoagulation reactor does not have to be shut down or be takenoff-line while the plates are changed out.

Applicants provide yet another advantage in providing in FIG. 1F,structure defining bumpers 28. This will allow the cartridge 14, as itis lifted in or out of the tank 12 to be protected from banging directlyinto the inside surface of the sidewalls of the tank or the bottom ofthe tank. Bumpers 28 may be made out of hard rubber or any othersuitable, durable, non-reactive material.

FIGS. 4, 5, and 6 all illustrate an alternate preferred embodiment of anelectrocoagulation cell 10 which doubles the capacity of theaforementioned electrocoagulation cells by providing tank 12 with alarger volume, typically about twice to four times the volume of thecell set forth in the earlier embodiments. The size of the cartridge 14is also increased, that is, to handle many more plates. An intermediatewall 30 is provided in the cartridge for structural support. It is alsoseen that there may be a pair of sump portions 12J each one with a drainsump 12P. The drain sumps are provided to remove any sediment settlingin the sumps. There also may be two or more drains 12H.

Applicants' open top, unpressurized parallel flow reactor may have anumber of plate arrangements including: plus minus plus minus: plus nminus n plus n minus, etc. The recirculation loop may recirculatethrough one or more cells of the reactor. Typically, water will flowthrough each individual solid reactor from bottom to top, to assist inthe escape of gases. Individual plates of each cell may be tabular innature and made from iron, steel, aluminum or other material. They mayinclude “cutouts” in various shapes (see FIG. 8B) to help generate anon-uniform and more varied e-field between the plates. Extra difficultwaters may be treated a number of passes through the cells through theuse of a recirculation pump (see below). There may be a number of waterinlets across the bottom of the housing of the parallel flow reactor tohelp generate even flow across the plates.

FIGS. 7A through 7E illustrate components of Applicant's cell stand 40.FIG. 7A represents a left and right side assembly for the rectangularstand. FIG. 7B is a rear assembly for the stand. FIG. 7C is a frontassembly for the stand. FIG. 7D is a view of a cross brace for use withthe rear assembly of the stand. FIG. 7E is another cross brace for usewith the front assembly of the stand.

When bolted together the front assembly, rear assembly and two sideassemblies form a rectangle which will vertically support the cell tank12 at a point immediately below the lower perimeter of the cartridge 14that is placed in the tank so as to avoid any sheer or flex loading onthe bottom walls of the tank. That is, when bolted together the cellstand 40 will have upper perimeter walls that are dimensioned identicalto at least a portion of the lower perimeter of the cartridge.

It is seen that electrocoagulation cell stand 40 has a number ofvertical support legs 42 for providing a vertical support to tanksupport perimeter members 44A, 44B and 44C. The tank perimeter supportmember 44A provides support to the left and right side of the tank, 44Bprovides support to the tank directly beneath the rear wall of thecartridge and vertical support perimeter 44C provides vertical supportto the tank directly below the front wall of the cartridge. Fasteners45A are used to fasten the stand together by engaging bolt holes 45B.Note that both the rear assembly of the stand and the front assembly ofthe stand include cross braces 46 and 48, with cross brace 46 on therear assembly of the stand including a vertical support leg 42 forreaching all the way to the floor. (See FIG. 7B) Compare this to FIG. 7Cwhich illustrates the front assembly of the stand. Here there is nothird leg. This is because the tank illustrated in FIG. 1 has a soliddrain 12P which projects horizontally out from the side wall. Further,note with reference to FIG. 1 that placement of a stand beneath the tankso as to brace the stand directly beneath the lower perimeter of thecartridge requires that the tank support members 44A, 44B and 44C mustbe attached so that vertical support member 44C will lay between the twodrains 12H and sump sidewall 12K. The rear tank support perimeter 44Cwill lay between the two inlet blanks 13M and the sidewall of sumpportion 12J. However, the third vertical support leg 42 shown in FIG. 7B(the one between the two outer support legs) is used since there is nodrain on the rear portion of the tank. The two sidewall portions of tanksupport perimeter 44A will lay beneath the sidewalls of the lowerperimeter of the cartridge and snugged against the sidewalls definingsump portion 12J. Applicant's unique cell stand 40 has the uniqueability to bolt together around the upper perimeter of sump portion 12Jof cell tank 12 in an manner that by, unbolting the six (6) bolts andbolt holes, the six (6) fasteners illustrated in FIGS. 7B and 7C one cantake apart the stand around the sump portion so as to provide clearancefor the solid drain 12P.

FIGS. 8A and 8B illustrate the first plate 20, which is seen to betabular and solid. Applicants have found that efficiency may beincreased by providing an alternate preferred embodiment here plate 21which includes cutouts 21A in the walls thereof. It is believed thatcutouts generate disturbances in the uniformity of the electromagneticfields between the plates and therefore assist in the efficiency of theelectrocoagulation units. However, they typically are also moreexpensive than providing plates without cutouts as set forth in FIG. 8A.

Typically, a reactor is rated at a given flow rate and works mostefficiently at that flow rate. For example, a 350 GPM parallel flowelectrocoagulation reactor is preferably not run at less than 50 gallonsper minute. Applicants provide, in FIGS. 9 and 10, a means forrecirculating a portion of the water exiting an electrocoagulationreactor and thereby achieving a net flow downstream from the reactor oftreated water of a flow rate less than that of the water flowing throughthe reactor. For example, a flow rate of 200 gallons per minute may bemaintained through a reactor with a recirculation loop drawing off partof the water exiting from the electrocoagulation reactor andreintroducing it upstream of the inlet of the electrocoagulationreactor. A net flow of, for example, 100 gallons per minute of treatedwater may result while maintaining a given flow rate at 200 gallons perminute through the electrocoagulation reactor. In other words, anoverall flow rate of 200 gallons per minute (for example) may bemaintained through the electrocoagulation reactor portion of the systemby using a recirculation pump and recirculation loop while treating anet amount of water equal to, for example, with reference to

FIG. 9, 100 gallons per minute. The use of a recirculation loop mayincrease the residence time for a particular waste that needs extratreatment. The alternative would be to have two reactors, two rectifiersetc., which would be costly.

A recirculation loop may be used with any of Applicant's embodimentsdisclosed herein, in fact with any other electrocoagulation reactor orsystem. It provides a fairly simple and inexpensive means to maintain agiven flow rate through a reactor while increasing the residence time ofthe water in the reactor (compared to a single pass) and, for decreasingthe net flow of water treated but maintaining a higher flow rate throughthe reactor. For example, assume upstream pump (100) is pumping 100gallons a minute from a water source (WS). Reactor (102) may be a 350gallon per minute reactor. At this flow rating, there is sufficient flowthrough the reactor to properly scrub the plates and efficiently treatthe water. One can use a recirculation pump (104) providing flow at therate of 250 gallons per minute to provide a flow rate through a reactorof 350 gallons per minute. Yet the net treatment rate is 100 gallons perminute of waste water flow downstream from a recirculation junction(106). In fact, Applicant's may increase the flow rate through a reactorproviding a flow rate greater than the rating for the reactor, whichflow rate may provide additional water velocity to scrub the plates. Forexample, a flow rate of 400 gallons per minute may be provided throughthe reactor while the net waste water treatment may be 100 gpm or less.

Turning now to FIG. 9, Applicant discloses a vessel or other source ofwater (WS), the water being industrial and/or biological and/or otherform of water that may contain contaminants that include organic and/orinorganic compositions. The water may be used in agricultural,industrial, domestic treatment or processing of other material, such assugar cane juice. It may be any water whose physical, chemical and/orbiological characteristics may be altered by electrocoagulation. It isseen that there is an intake pipe having several sections (108A, 108Band 108C) for carrying water from the water source into a reactor (102),typically an electrocoagulation reactor. In line with the intake pipemay be an upstream pump (100), upstream of the reactor or the reactormay simply be lower than the water source, the “head” providing impetusto the movement of water to the reactor. The intake pipe may include asection (108A) between the water source (WS) and the upstream pump(100). A second section of intake pipe (108B), may be located between anupstream pump (100) and a T Junction or other junction (110). Finallythere may be a section of intake pipe (108C) between the T Junction orother junction and an intake port (112) of the electrocoagulationreactor (102).

The upstream pump (100) may be used to flood the reactor and provide forwater fluid flow through the reactor or the “head” of the water sourcemay serve the same function. The reactor also has an outlet port (114)and outlet pipe sections (114A and 114B). Water leaves theelectrocoagulation reactor at outlet port (114). Some of the water willbe recirculated by exiting the outlet pipe at recirculation junction(106), being drawn by a recirculation pump (104) through a recirculationloop (116). Recirculation loop (116) may include pipe section (116A)upstream of recirculation pump (104) and a recirculation pipe section(116B) downstream of recirculation pump (104). Recirculation pipesection (116B) joins the intake pipe downstream of upstream pump (100)(if any) and upstream of intake port (112), here at junction (110).

FIG. 10 illustrates an alternate preferred embodiment of Applicants'novel recirculation loop here being illustrated in use with a reactorcomprising two cells, first cell (102A) and second cell (102B). Thesecells may be either a series flow reactor cell or Applicants' novelparallel flow reactor cell disclosed herein. Here it is seen thatApplicants provide a pipe or channel (120) connecting the two cells. Thefirst cell (102A) has an inlet (122A) and an outlet (122B). Second cell(102B) has an inlet (124A) and an outlet (124B). Pipe (120) connects theoutlet of the first cell to the inlet of the second cell. Downstream ofthe outlet of the second cell is a T-junction (126) at which water maybe recirculated through recirculation loop (116) under the impetus ofrecirculation pump (104) to a point upstream of inlet (122A) of firstreactor (102A). Note that this embodiment illustrates flow through thereactor cells under the impetus of gravity or a “head” between a watersource (not shown) which is higher than the first cell, and the firstcell which is higher than the second cell. Water continuing downstreamof T-junction (126) will continue on for either use discharge, orfurther treatment, as in settlement, clarification, gas assistedflotation or the like.

One of the purposes in the parallel flow reactor of providing arecirculation loop is to increase the probability of an ion of wastecomposition being adjacent an oppositely charged plate. In pressurizedreactors (such as Applicants' series flow reactor), sufficient velocityof liquids through the reactor must be maintained for proper removal orscrubbing of the plates of the reactor. On the other hand, inApplicants' parallel flow reactor, which is typically run at atmosphericpressure, sufficient flow is necessary to increase the opportunity of acharged ion to be adjacent an oppositely charged plate.

One way in which a recirculation loop may be used is to replace therequirement for multi-cell electrocoagulation reactor. For example, if atreatment job may require 200 g.p.m. through two cells, one followingthe other (see FIG. 10) for effective treatment. A single cell with arecirculation loop may achieve equivalent effective treatment of the twocell unit.

Applicants discloses in FIGS. 11A, 11B, 12A and 12B an inventionrelating to a gas-assisted flotation process and apparatus to assist inthe separation of solids and liquids from a slurry, such as a slurrythat would come out of an electrocoagulation reactor cell. Suchinvention may be used to treat wastewater or any other water or fluidthat may be used in or result from a manufacturing process. Applicantsprovide an apparatus and process by which water received from anelectrocoagulation cell may be treated on a continuous basis for theseparation of solids therefrom. For example, water may be treated toremove silicon therefrom for use in the process of manufacturing brownsugar. Indeed, none of the inventions and processes set forth in thisapplication need be confined to “wastewater,” but can be applied to thetreatment of any water whose characteristics are intended to be alteredsuch as for example, by treatment in an electrocoagulation reactor. Thedisclosed invention and process may be used downstream of anyelectrocoagulation cell or other treatment apparatus, including anelectrocoagulation reactor with parallel flow or series flow. Further,some water may be passed through the gas-assisted flotation process andapparatus more than once, as by using Applicants' novel recirculationloop. Under some circumstances, Applicants' novel gas-assisted flotationprocess and apparatus may replace the defoam, sludge, thickener andclarifier processes and apparatus.

Applicants' novel apparatus, a gas-assisted flotation cell, is providedwhich has a conical upper chamber that tapers into a neck portion, whichneck portion may include a manifold with gas intake jets to assist inlifting and propelling floated solids residing above a liquid level, outof a removed end of the neck for discarding or for further treatment, asliquid is drawn off the bottom of the main chamber for either reuse orfurther treatment.

Applicants' gas-assisted flotation cell provides advantages not found inthe prior art, including U.S. Pat. No. 5,055,184 (Carpenter, et al.1991), the specifications and drawings of which is incorporated hereinby reference. The Carpenter reference discloses generally a gas-assistedflotation apparatus for separating solids from liquids in a slurry. Itcomprises a main chamber, an inlet channel from which a liquid slurrymay enter, and an upper tapered portion. Gas bubbles attached to solidsand particles will tend to float upward in the main chamber and resideabove a liquid line. When the level of liquid is sufficiently high inthe chamber, the material floating above the liquid line will eitherdrop off through a side exit pipe above the tapered chamber or, if agas, will rise upward as through a chimney. Thus, the Carpenterreference discloses two exits ports for expelling material rising abovea liquid surface and, in addition, requires a valve mechanism to controlthe level of liquid in the main chamber.

Among the advantages of Applicants' present invention over the Carpenterreference is the positive removal, as by compressed gas, of floatingsolid material out of a removed end of a neck that is in fluidcommunication with the opening at the apex of the tapered walls of theupper chamber. Further, Applicants provide a simple method ofmaintaining a liquid level in the main chamber sufficient to presentmaterial floating above such level to the compressed gas injected intothe neck of the main chamber. Further, Applicants provide a noveltapered lower chamber for collection of sediment therein and, further,for a novel stilling chamber suspended within the main chamber. This andother novel features of Applicants' gas-assisted flotation process andapparatus will be apparent with reference to the drawings below.

FIGS. 11A and 11B illustrate a dissolved air flotation apparatus 200 andFIGS. 12A and 12B show an alternate preferred embodiment, dissolved airflotation apparatus 200A.

The figures illustrate a main chamber 202 including a tapered upperchamber 204. Main chamber 202 includes vertical sidewalls 206.Applicants provide a tapered lower chamber 208 which descends below thevertical sidewalls 206 and terminates in a drain 210 that may have aplug, removable therefrom, for the draining of sediment that may collectthereon. Tapered upper or lower chambers may be conical or polygonallyshaped.

Turning back to the upper chamber, it is seen that tapered upper chamber204 reaches an apex that is open and in fluid communication with a neck212. In FIGS. 11A and 11B, it is seen that Applicants provide a sideport214 for removal, as by descent under the impetus of gravity, of solidsfloating on the top of a liquid/solids interface. In FIGS. 11A and 11B,it is seen that there is a removed neck opening 216 for the escape ofgases therefrom. However, turning to FIGS. 12A and 12B, it is seen thatApplicants may provide, at a suitable location, as for example in theneck 212 (alternatively directly in the walls of tapered upper chamber204), an air injector assembly 218. The purpose of the air injectorassembly is to inject air, or other gas, at a suitable location, such asin the neck, to assist in lifting the solids and the gases entrapped inthe solid/liquid froth that is “floating” above the liquid interface,out of a removed end (216B) of a transport tube 216A which may transportthe air charged mix. Applicants' air-injected assembly includes acompressed gas source 218A (for example, an air pump or a compressed airtank) and a delivery tube 218B for delivery of a gas, under pressure toa manifold 218C, which manifold is in fluid communication with one ormore jet 218D or pressure ports for injecting the air or other gas undercompression into the neck of the main chamber and into a solid/gas frothfor removal from the removed end (216B) of transport tube 216A.

Applicants' novel gas-assisted flotation apparatus 200, 200A may includea stilling chamber 220, the stilling chamber including an inlet tube 222for carrying a liquid, typically with a flocculant or precipitantsuspended therein into the stilling chamber. Applicants' inlet tube 222may be seen to have an open removed end 222A, and, adjacent a removedend an angled portion 222B for directing the flow of liquids into thestilling chamber so as to generate a slow, non-turbulent flow within thechamber. Upstream of the point at which the inlet tube enters the mainchamber, there may be a degas vent or pipe 224 from which the larger gasbubbles may escape from the liquid before it enters the main chamber.Entering the stilling chamber 220 through a dissolved air delivery tube226 is a compressed gas liquid composition. The dissolved air deliverytube includes a removed end 226A which may include an angled portion226B in an effort to assist in the circulation of the fluid in the mainchamber to avoid turbulence. Indeed, the function of stilling chamber 24is to reduce the velocity of liquid entering the chamber to a point ofslow, smooth flow. Stilling chamber 220 also is intended to increaseretention time to allow further coagulation, flocculation and gas bubbleprecipitation as well as a growth of flocculant solid particles. Notethat stilling chamber 220 may include a flanged lip 228 adjacent anupper opening thereof and a sloped bottom wall 232, the flanged lip andsloped bottom wall connected by vertical sidewalls 230. The effect ofthe flanged lip and/or sloped bottom wall is to promote a smooth, slowflow of the liquid and thus provide increased efficiency. Notice thatopen bottom 234 of stilling chamber 220 may be located above drain 210so as to “allow” any precipitates descending therefrom to travel towardthe drain. Note also that the sidewalls of the stilling chamber mayinclude an interior baffle 236 projecting into the stilling chamber soas to reduce the flow of liquids therein to, again, promote a smoothnon-turbulent slow flow of liquid. Furthermore, the stilling chamber maybe supported within the main chamber, above the floor of the mainchamber by chamber support baffles 238 extending from an inner surfaceof the vertical sidewalls of the main chamber to the sidewalls of thestilling chamber, the support baffles having an exaggerated width(vertical dimension) so as to help minimize currents in the mainchamber.

The main chamber must be provided with a means to remove a liquidtherefrom, the liquid here being removed by outlet channel assembly 240which may consist of a single pipe, having multiple branches 240A, 240Band 240C (see FIGS. 11A and 11B) or a jacket assembly 240D (see FIGS.12A and 12B). By providing for multiple outlets at or near the bottom ofmain chamber 202, Applicants provide for a more efficient removal ofliquid from the gas-assisted flotation apparatus 200, 200A. While threebranches are illustrated in FIG. 11B, any number may be used.

Applicants may also provide a standing pipe 242 with a catch vessel 244from which liquid removed from the main chamber through outlet channelassembly 240 may be contained, for the control of the level of liquid inmain chamber 202 and as a source of water for the air dissolvingmechanism.

So long as fluid to be treated is allowed to enter chamber, the fluidwill rise to the level of the top of standing pipe 242. This level maybe adjusted to coincide with the level of the bottom of the sideport 214or to a level just below jets or pressure ports 218D, or to any bothappropriate for the density of the floating phase.

Thus, Applicants provide a novel gas-assisted flotation process andapparatus that achieves at least the following results: reduction ofturbulence; effective removal of gas/solid material through a removedneck opening; effective maintenance of fluid level adjacent a gas orcompressed air transport tube; an effective drain to removeprecipitates; the angled injection of fluid into a stilling chamber andgas dissolved air from a separate tube into a stilling chamber, thestilling chamber being effectively designed to help reduce turbulence.Dissolved gas is injected through dissolved air delivery to be 226.Water is drawn off the bottom of catch vessel 244. Air pump 244A willinject air into the stream of fluid injected into the stilling chamber.Outlet port 244B will pass water on for further treatment or use.

Thus, applicants provide a method of transporting a quantity of waterfrom a removed location to an electrocoagulation reactor, moving thewater through the electrocoagulation reactor while subjecting the waterto an electric field, then discharging the waste water from theelectrocoagulation reactor through a discharge port. Downstream thedischarge port and inline with discharge piping is a recirculation loopthat includes a pump for recirculating a portion of the water back intothe electrocoagulation reactor by reintroducing the waste water that isalready passed through the reactor at least once upstream of the inletport of the reactor.

I claim:
 1. A system for treating water, the system comprising: amultiplicity of reactor plates; a cartridge adapted to removably receivea multiplicity of the plates therein and maintain the plates in parallelalignment; a cell tank adapted to receive the cartridge with reactorplates loaded therein such that the cartridge is substantially insidethe cell tank when received, wherein the cartridge may be removed fromthe cell tank to replace one or more reactor plates, the cell tankhaving an intake pipe and a discharge pipe; a pump adapted to convey aquantity of water from a distant location to the intake pipe and intothe cartridge; and an electrical conduit adapted to convey an electricalsignal to the reactor plates to subject water moving between the platesto an electric field.
 2. The system of claim 1, wherein the cartridge isconfigured such that water flowing therethrough moves upwards betweenthe plates.
 3. The system of claim 2, wherein the cartridge has firstwall and a second wall, the first wall shorter than the second wall suchthat water flows over the top of the first wall after moving upwardsbetween the plates.
 4. The system of claim 3, wherein the cell tankincludes a portion for receiving the water flowing over the top of thefirst wall.
 5. The system of claim 1, further comprising a recirculationloop for taking a portion of the water in the output pipe andreintroducing it to the inlet pipe.
 6. They system of claim 5, whereinthe recirculation loop comprises a positive displacement pump.
 7. Thesystem of claim 5, wherein the recirculation loop includes a pipe forjoining the outlet pipe and for joining the inlet pipe downstream of thepump.
 8. The system of claim 1, wherein the pump is a positivedisplacement pump
 9. The system of claim 1, wherein the cell tank has anopen top and the receipt and removal of the cartridge are accomplishedthrough the open top.
 10. The system of claim 1, further comprising asecond cell tank in series with the first cell tank.
 11. The system ofclaim 1, wherein the cartridge includes a multiplicity of slotsdimensioned to receive a reactor plate.
 12. The system of claim 1,wherein the cell tank includes a sump portion adapted to gather wastefrom the water.
 13. The system of claim 1, further comprising handlingstraps adapted to engage the cartridge and to assist in handling of thecartridge.
 14. The system of claim 1, wherein some of the plates have ashorter height than others of the plates.
 15. The system of claim 1,further comprising a water clarifier adapter to clarify the waterdischarged from the cell tank.
 16. The system of claim 1, furthercomprising an electrocoagulation reactor downstream of the cell tank,the electrocoagulation reactor adapted to subject the water dischargedfrom the cell tank to an electric field.